Portable deployable underground communication systems, devices and methods

ABSTRACT

Disclosed are passive reflector radio communications systems, such as for UHF frequencies or greater than UHF frequencies, and related deployment systems and devices that provide underground communications. Embodiments of the system include reflector elements to provide passive radio communications, structural frameworks to support and orient the reflector elements, methods for calculating reflector size, shape, and position corresponding to a desired wavelength, and deployment methods and devices to install the communication system at a desired location. The passive reflectors can be placed in a folded or otherwise compact mode, for transport into underground tunnels. Once at the desired installation location, the system can be installed, with the reflectors positioned appropriately for the radio frequencies used at the location. Some of the embodiments include any of vertical or horizontal foldable reflector poles, reflective sheets, reflective mesh sheets and/or ropes, inflatable reflective pucks, and rapid deployment systems and methods.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims priority to U.S. patentapplication Ser. No. 15/877,281, filed Jan. 22, 2018, which is acontinuation of and claims priority to U.S. patent application Ser. No.15/439,761, filed Feb. 22, 2017, which issued as U.S. Pat. No. 9,876,556on Jan. 23, 2018, which claims priority to U.S. Provisional ApplicationNo. 62/298,297, filed Feb. 22, 2016, which each is incorporated hereinin their entirety by this reference thereto.

GOVERNMENT RIGHTS

This invention was made with government support under subcontract numberSUB2015-AM-001-MIN awarded by prime contractor Robotic Research, LLC,under prime contract number W15QKN-14-C-0045 to the Defense ThreatReduction Agency (DTRA). The government has certain rights in theinvention.

FIELD OF THE INVENTION

At least one embodiment of the present invention pertains to passivereflectors for wireless communication systems. More particularly, atleast one embodiment of the present invention pertains to portablereflector components that can readily be positioned and deployed withina constrained environment, such as within an underground environment, toenable wireless communication between mobile radios.

BACKGROUND

Radio communications in underground and constrained environments such asmine tunnels is a complex challenge. The transmission of radio wavesthrough the earth is limited due to severe attenuation of the signals,and most practical methods for communication use the tunnels themselvesas paths for the radio waves. However, as radio waves travel in straightlines, and mine tunnels frequently change direction, curve, or intersectwith other tunnels and shafts, it is necessary to install a complexinfrastructure of radio equipment within mining tunnels to facilitatereliable communications between operators within the mine shaft and withpersonnel above ground.

Similar challenges and constraints occur in a variety of environmentsand situations. Cave exploration, as an example, is carried out inconstrained conditions, with little or no knowledge of the terrain andthe layout of underground pathways. In such applications, radio signalsfrom an external source will have limited reach, such that repeaters areoften needed to ensure communications for the exploring party. Inaddition to underground complexes, challenging environments for radiocommunications exist in mountainous and canyon environments. In covertor military operations, there may be an existing radio communicationsinfrastructure; however, it may be unavailable to the military team whomay need to operate using different equipment and radio frequencies, asit is unlikely that they will have access to communications systems thatmay be controlled by potential adversaries.

Mining and underground tunnels are typically highly constrained in termsof space. It is thus valuable to have solutions that are compact or thatotherwise take up little volume, especially within the pathways of thetunnels. Tunnels can extend to many kilometers underground, and allequipment must be transported to the installation location, often byoperators traveling on foot or using very small vehicles. Equipment thatis light and easy to transport is thus also valuable.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the present invention are illustrated by wayof example and not limitation in the figures of the accompanyingdrawings, in which like references indicate similar elements.

FIG. 1 is a schematic view of illustrative embodiment of a portabledeployable underground communication system.

FIG. 2 is a flowchart of an illustrative process for deploying aportable underground communication system.

FIG. 3 shows an illustrative embodiment of a passive reflector elementthat includes a structural pole, and coaxially positioned reflectors.

FIG. 4 shows an illustrative embodiment of a storable passive reflectorelement in an undeployed state.

FIG. 5 shows a close-up view of reflector elements for an illustrativeembodiment of a passive reflector element.

FIG. 6 shows a 3D radiation pattern image for an illustrative embodimentof a passive reflector element having a vertically-aligned structuralpole and coaxially positioned reflectors, which provides 360 degreecoverage in the horizontal plane.

FIG. 7 shows vertical and horizontal radiation patterns for anillustrative embodiment of a passive reflector element having avertically-aligned structural pole and coaxially positioned reflectors.

FIG. 8 shows an illustrative embodiment of a passive reflector componenthaving a structural pole with pairs of reflectors in the horizontalplane stacked on the vertical axis.

FIG. 9 shows a close up view of the reflector pair of the passivereflector component seen in FIG. 8.

FIG. 10 shows a 3D radiation pattern image for an illustrativeembodiment of a passive reflector element having pairs of reflectors inthe horizontal plane, which provides 360 degree coverage in thehorizontal plane.

FIG. 11 shows vertical and horizontal radiation patterns for anillustrative embodiment of a passive reflector element having pairs ofreflectors in the horizontal plane.

FIG. 12 shows an illustrative embodiment of a passive reflectorcomponent having a structural pole with horizontal reflectors andvertical reflectors.

FIG. 13 shows a close-up view of the reflector elements seen in FIG. 12.

FIG. 14 shows an alternative arrangement of a passive reflectorcomponent having a structural pole with horizontal reflectors andvertical reflectors.

FIG. 15 is a chart that shows vertical and horizontal radiation patternsfor an illustrative embodiment of a passive reflector element havinghorizontal reflectors and vertical reflectors.

FIG. 16 shows an illustrative passive sheet reflector component thatincludes reflector elements arranged in a two-dimensional matrix.

FIG. 17 shows detailed view of a single-reflector element for anillustrative passive sheet reflector component.

FIG. 18 shows a prototype implementation of an illustrative passivesheet reflector component, including a structural sheet and a 4×4 matrixof copper tape reflector elements.

FIG. 19 shows a 3D radiation pattern image for an illustrativeembodiment for one reflector element of a passive sheet reflectorcomponent.

FIG. 20 is a chart that shows vertical and horizontal radiation patternsfor an illustrative embodiment of a passive sheet reflector component.

FIG. 21 shows an illustrative view and a 3D radiation pattern image foran alternate implementation of an illustrative embodiment for onereflector element of a passive sheet reflector component.

FIG. 22 is a chart that shows vertical and horizontal radiation patternsfor an alternate implementation of an illustrative embodiment for onereflector element of a passive sheet reflector component.

FIG. 23 shows an illustrative view and a 3D radiation pattern image fora further implementation of an illustrative embodiment for one reflectorelement of a passive sheet reflector component.

FIG. 24 is a chart that shows vertical and horizontal radiation patternsfor the implementation of an illustrative embodiment for one reflectorelement of a passive sheet reflector component shown in FIG. 23.

FIG. 25A and 25B provide a schematic front and rear views of reflectorelements for an illustrative embodiment of patch antenna panels.

FIG. 26 shows an illustrative far field 3D radiation pattern for acorresponding patch antenna panel embodiment.

FIG. 27 is a chart that shows vertical and horizontal radiation patternsfor an illustrative embodiment of patch antenna panels.

FIG. 28 shows conceptual 3D radiation patterns for two interconnecteddual patch antenna panels.

FIG. 29 provides a schematic view of a passive reflector component thatincludes an inflatable puck having deployable structural elements andreflector elements.

FIG. 30 shows a plurality of inflatable pluck passive reflectorcomponents in their deployed state.

FIG. 31 provides a schematic view of a flat panel passive reflectorcomponent, using a metallized reflector element and a plastic tarpaulinstructural element.

FIG. 32 provides a schematic view of duel pole passive reflectorcomponents, wherein each passive reflector component includes astructural pole with coaxially-positioned dual reflectors.

FIG. 33 shows 3D radiation patterns for one reflector element in a duelpole passive reflector.

FIG. 34 is a chart that shows vertical and horizontal radiation patternsfor one reflector element of an illustrative dual pole reflectorassembly.

FIG. 35 is a schematic diagram 780 for illustrative placement of a dualpole reflector assembly 14 h in a tunnel network, which showscorresponding radiation patterns and preferred communication directions.

FIG. 36A and 36B are a schematic diagrams 800,820 for illustrativehelical wire reflector components.

FIG. 37 shows 3D radiation patterns for one helical wire reflectorelement associated with a helical wire reflector component.

FIG. 38 is a chart that shows vertical and horizontal radiation patternsfor one helical wire reflector element associated with a helical wirereflector component.

FIG. 39 is a schematic diagram 880 of a deployed balloon reflectorcomponent in a tunnel network.

FIG. 40 is a schematic view of a deployment module for a balloonreflector component.

DETAILED DESCRIPTION

References in this description to “an embodiment”, “one embodiment”, orthe like, mean that the particular feature, function, structure orcharacteristic being described is included in at least one embodiment ofthe present invention. Occurrences of such phrases in this specificationdo not necessarily all refer to the same embodiment. On the other hand,the embodiments referred to also are not necessarily mutually exclusive.

When radio communications reach the extent of their transmitted range,they may be propagated beyond their initial range through the use ofrepeaters. Repeaters use antenna reflector elements to receive thetransmitted signal and retransmit it. Such retransmission may use theoriginal frequency, signal direction, polarization, and othercharacteristics, or introduce changes in any or all of these aspects tomeet the specific needs of a situation. Repeaters may be active, thatis, using electric power to retransmit the received signal, or passive,retransmitting the received signal without the use of electric power.Repeaters are typically designed for specific frequency ranges ofoperation.

Existing solutions to the problem of radio communications in undergroundtunnel complexes typically use active repeaters placed at judiciousintervals along the tunnels to repeaters require a power source, whichmust be provided either by electric wiring throughout the tunnel systemor by batteries, which then must be monitored and replaced as necessary.Some attempts have been made to use simple passive reflectors, usingsquare sheets of aluminum, in mines.

It is time-consuming and expensive to implement an electrical system insituations where there is an urgent need for communications in aconstrained environment, for example during exploration of undergroundfeatures such as caves and tunnels, in search and rescue operations incollapsed mines or buildings, and in military situations (especiallycovert military operations) where the surrounding infrastructure may notbe in place or may not be accessible to the military users. In certainsituations such as the initial exploration or surveying of a convolutedunderground complex, it is not possible to implement an active repeatersystem prior to the survey.

Previous approaches to passive reflectors have been limited, using largeflat sheets of aluminum positioned at an angle of 45° to the incidentradio wave, and were intended to provide a small extension in range inthe context of intersecting cross cuts in mines or large corridors.

It would therefore be advantageous, in underground and constrainedenvironments, to implement a portable, easily deployable, passive radiocommunications solution. Specifically it would be advantageous toimplement portable, easily deployable, passive reflector systems, suchas configured to operate in the ultra-high-frequency (UHF) band (300MHz-3 Ghz range), or in frequencies equal to or greater than the UHFband, e.g., such as up to 5 Ghz.

Disclosed herein are portable, passive radio communications systems,components and related processes that can readily be deployed and usedin underground and constrained environments. Certain embodiments provideportable, easily deployable, passive reflector systems, such asconfigured to operate in the ultra-high-frequency (UHF) band (300 MHz-3GHz range) or at frequencies equal to or greater than the UHF band,e.g., such as up to 5 Ghz.

The disclosed passive reflector radio communications system typicallyincludes several novel aspects: patterned arrays of reflector elements,structural frameworks to support and orient the reflector elementswithin the array, methods for the calculation of reflector element andreflector element array size, shape, position, and orientationcorresponding to a desired operational frequency, and deployment methodsand devices to install embodiments of the invention at the desiredlocation.

In some embodiments, reflector elements that are appropriate for theradio frequencies typically used in mining or other constrainedenvironments can preferably be implemented.

For example, half-wavelength reflector elements can be used, subject toadjustment factors based on the material used in their construction andtheir size and thickness. The reflector elements can be any ofstructures such as rods or poles; shapes such as rectangular, square, orsimilar polygonal strips or panels; constructions such as woven orbraided fibers, threads, or wires; and arrangements such as linear, twodimensional, or three-dimensional arrays; individually or in arrays ofsimilar or dissimilar elements.

In some embodiments, the passive reflector elements are supported andcan be positioned and oriented by a collapsible framework. The frameworkmembers can include spring-loaded struts, inflatable struts, flexiblepoles, hollow poles, inflatable tubes, foldable sheets, or collapsibleropes. The framework supports the reflector elements and orients itrelative to the structure. While the structural framework inillustrative embodiments of the invention is intended to support andorient passive reflector elements, it can be readily envisioned tosupport and orient active reflector elements as well.

The structures, shapes, constructions, and arrangements of the reflectorelements, their positions, and their material composition can bedetermined based on the desired operational frequencies and the specificpropagation characteristics that are desired in the undergroundenvironment. For example, the specific embodiments described below usecertain materials, dimensions, and positions that are the result ofthese considerations.

The passive reflector system can be placed in a folded or otherwisecompact mode for transport into the tunnels. Once at the desiredinstallation location, the system can be installed and the reflectorelements positioned appropriately for the radio frequencies used at thelocation.

FIG. 1 shows an illustrative view of a passive communication system 10,in which two users USR are considered using wireless devices 18, e.g.,18 a,18 b, in an underground tunnel network ENV. The radiocommunications 20 emitted by the first user's wireless device 18 a arepropagated 20 using passive reflector elements 14, such as shown atsuccessive locations 16 a-16 i through the tunnel ENV, so that thecommunication signals 20 are reflected from successive reflectorelements 14, to reach the second user's device 18.

FIG. 2 is a flowchart of an illustrative process 40 for deploying aportable underground communication system 10. In the illustrativeprocess seen in FIG. 2, constraints for deployment of a communicationsystem 10 using passive reflector components 14 can be obtained 42, inwhich the constraints can include one or more available modes oftransport for the components, such as to be carried by humans, packanimals, vehicles, and/or cable mechanisms. The specific passivereflector components 14 can also be selected 44 from an inventory ofavailable components, such as based on any of identified constraints.The passive reflector components 14 are also typically required to betransported 46 through the constrained environment ENV. Before or at thetime of deployment, the locations for deployment of the passivereflector components can be identified 48 and selected 50. Upondeployment 52 of the selected passive reflector components 14, thesystem 10 can be established or extended within the constrainedenvironment.

Reflector Element and Array Design

Some embodiments of the Illustrative reflector elements in the inventionare designed using dipole design principles. A typical antenna dipole isconstructed with two conductive segments. A feedpoint between the twoconductive segments provides a signal for transmission in the case of atransmitting dipole antenna, and serves as a sink for the receivedsignal in the case of a receiving dipole antenna. Dipoles are high-gain,omnidirectional antennas, and are well suited for use in collineararrays—a stacked set of vertically aligned dipoles provides high gain inthe horizontal plane.

To obtain such advantages with the use of reflector elements, someillustrative embodiments of the passive reflector components 14 adaptdipole design to that of the reflector, such as seen in FIG. 3. In apassive reflector system 10, the reflector 68 can be considered to be adipole that is “fed” by an incident wave, and thus does not require afeedpoint to transmit. Further, the received signal 20 is not sunk intothe feedpoint, but is instead reradiated. The ends of the dipolesegments that would normally be connected to the feedpoint can beconnected to each other for simplicity. This approach to reflectorelement design has advantages in design and construction, and provides awider bandwidth, especially in higher harmonics. The resulting reflectorelements 68 can be stacked, and arranged in collinear arrays 66, such asseen in FIG. 3, for improved gain and directionality due to theinteraction between the reradiation patterns from the different elements68 in the array 66.

Foldable Pole Reflector Component having Vertical Reflector Elements.

FIG. 3 shows an illustrative embodiment of a passive reflectorcomponents 14 a that includes a structural pole 62, and coaxiallypositioned reflectors 68. FIG. 4 shows an illustrative embodiment of astorable passive reflector component 14 a in an undeployed state. FIG. 5shows a close-up view of reflector elements 68 for an illustrativeembodiment of a passive reflector component 14 a.

In this embodiment, the structural framework for the passive reflectorsolution is a foldable pole arrangement, using hollow poles 82 andmating ferrules 84, in which the hollow poles 82 can be made of asuitable dielectric material such as fiberglass. In some embodiments 14a, an elastic cord 86 is run through the hollow fiberglass poles 82,serving as a tensioning mechanism. The tubes 82 can be collapsed andfolded, as seen in FIG. 4, for transport and storage, and installed atthe location by interconnecting 88 the pole segments 82.

The reflector elements 68 seen in FIGS. 3-5 are vertically positionedalong the axis of the structural pole 62. In some embodiments, thereflector elements 68 are preferably hollow cylindrical tubesconstructed of a metal, e.g., aluminum, and placed coaxially and aroundthe structural pole 62. Alternatively, the reflector elements 68 can beconstructed using metal or metalized tape affixed around a hollow tube62 of any of a variety of materials.

The reflector elements 68 can be stacked on the pole 62 as shown in FIG.3, with an appropriate spacing between them. The length of the reflectorelements 68 can be selected to provide resonance at the desiredfrequency of operation. In some embodiments, the length can preferablyapproximate half the wavelength (0.5λ) of the signal, as adjusted by anappropriate adjustment factor corresponding to the material of thereflector and its size and thickness. The distance from the center ofone reflector 68 element to the center of the next reflector 68 canpreferably correspond to approximately 0.75λ adjusted as above.

As an example, a specific implementation of a passive reflectorcomponent 14 a includes eight aluminum reflector elements 68, fiberglasssupport poles 62, and can further include an aluminum support base 70.

In some embodiments of the reflector component 14 a seen in FIGS. 3-5,to support an illustrative UHF radio frequency of 400 MHz, the length ofeach reflector element 68 can be optimized to be 13.1″ for resonance,using a 0.5λ length, adjusted by an adjustment factor of 0.888. Thecenter-to-center distance between two adjacent reflectors 68 can beoptimized to 20.1″, or 0.75λ using the same adjustment factor. Thisarrangement provides a total maximum gain of 10.3 dBi. In such anillustrative embodiment, the antenna dimensions including the supportstructure are 0.625″×0.625×″198.3″ (16.5′).

In some embodiments of the reflector component 14 a seen in FIGS. 3-5,the reflector component 14 a can be placed on the ground within aconstrained environment ENV, taking up little space in the tunnel, or,alternatively, mounted on a wall. In some embodiments of the reflectorcomponent 14 a, the reflector elements 68 are cylindrical so that thesignal 20 will be reflected uniformly through all 360 degrees of thehorizontal plane, providing coverage in all directions.

FIG. 6 shows a 3D radiation pattern image 120 for an illustrativeembodiment of a passive reflector element 14 a having avertically-aligned structural pole 62 and coaxially positionedreflectors 68, which provides 360 degree coverage in the horizontalplane. FIG. 7 shows 140 vertical and horizontal radiation patterns m1and m2 for an illustrative embodiment of a passive reflector element 14a having a vertically-aligned structural pole 62 and coaxiallypositioned reflectors 68.

In some alternate embodiments of the passive reflector element 14 a,each reflector element 68 can be flat and oriented at a different angle,instead of cylindrical. This arrangement allows each reflector 68 to bedirectional, and the embodiment can provide a broad range of reflectionangles.

Passive Reflector Components Foldable Pole, with Horizontal ReflectorElements.

FIG. 8 shows an illustrative embodiment 160 of a passive reflectorcomponent 14 b having a structural pole 62 with pairs of reflectors 68 bin the horizontal plane stacked on the vertical axis Z. FIG. 9 shows aclose up view 180 of a illustrative reflector pair 182, e.g. 182 a,182b, of the passive reflector component 14 b seen in FIG. 8.

In the illustrative passive reflector component 14 b seen in FIG. 8 andFIG. 9, the structural framework 62 for the passive reflector component14 b can be configured as a foldable pole 62, such as discussed abovefor passive reflector component 14 a, using hollow poles made of asuitable dielectric material, e.g., fiberglass. As discussed above, insome embodiments 14 b, an elastic cord 86 can extend through matingfiberglass tubes 82, serving as a tensioning mechanism. In this manner,the tubes 82 can be collapsed and folded (FIG. 4) for transport andstorage, and assembled 88 installed at the location ENV byinterconnecting the pole segments 82.

The reflector elements 68 b are vertically positioned along the axis Z184 z (FIG. 9) of the structural pole. In some embodiments, eachreflector element 68 b includes a pair of crossed metal rods,intersecting at an angle of 90°. In some embodiments of the illustrativepassive reflector component 14 b seen in FIG. 8 and FIG. 9, thereflector elements 68 b can preferably be constructed of a metal, e.g.,aluminum. The reflector elements are stacked on the pole 62, with anappropriate spacing between them. In some embodiments, each of thecross-shaped reflector elements 68 b are aligned in the horizontal planeand are placed perpendicular to the axis Z 184 z of the structural pole62. The size, shape, spacing, and grouping of the reflector elements 68b can be configured to provide desired reflectivity characteristics forthe frequencies involved, i.e., optimized for UHF frequencies of higherthan UHF frequencies, e.g., such as but not limited to 2.4 Ghz or 5 Ghzoperation.

The length of the reflector elements 68 b can be selected to provideresonance at the desired frequency of operation. In some embodiments,the length can preferably approximate half the wavelength (0.5λ) of thesignal 20, as adjusted by an appropriate adjustment factor correspondingto the material of the reflector 68 b and its size and thickness. Insome embodiments of the reflector elements 68 b, the vertical distancefrom one pair of reflector elements 68 to the next pair 68 b correspondsto approximately 0.75λ, adjusted as above.

An illustrative implementation of the passive reflector component 14 bseen in FIG. 8 and FIG. 9 uses sixteen aluminum reflector elements 68 barranged in eight crossed pairs 182 a,182 b, aligned in the horizontalplane, fiberglass support poles 62, and can include an aluminum supportbase 70 (FIG. 3). To support an illustrative UHF radio frequency of 400MHz, the reflector element length can be optimized to be 13.8″ forresonance, using a 0.5λ length, adjusted by an adjustment factor of0.935. The vertical distance between two adjacent reflector crossedpairs can be optimized to 20.7″, or 0.75λ using the same adjustmentfactor. This arrangement provides a total maximum gain of 10.9 dBi. Inan illustrative embodiment, the antenna dimensions including the supportstructure are 13.8″×13.8″×180.9″ (15′). In some embodiments of thereflector component 14 b seen in FIGS. 8 and 9, the reflector component14 b can be placed vertically on the ground within a constrainedenvironment ENV, such as within a tunnel, resulting in a smallfootprint.

FIG. 10 shows a 3D radiation pattern image 200 for an illustrativeembodiment of a passive reflector element 14 b having pairs ofreflectors 68 b in the horizontal plane, which provides 360 degreecoverage in the horizontal plane. FIG. 11 is a chart 220 showingillustrative vertical and horizontal radiation patterns m1 and m2 for anillustrative embodiment of a passive reflector element 68 b having pairsof reflectors in the horizontal plane. The reflector elements 68 breflect the signal through a 360-degree arc in the horizontal plane witha slightly higher gain in the 45°/−135° axis, providing relativelyuniform coverage in all directions.

Passive Reflector Component having Horizontal and Vertical Reflectors.

FIG. 12 shows 240 an illustrative embodiment of a passive reflectorcomponent 14 c having a structural pole 62 that includes a combination68 c of horizontal reflectors and vertical reflectors. FIG. 13 shows aclose-up view 260 of the reflector elements seen in FIG. 12. FIG. 14shows an alternative arrangement 280 of a passive reflector component 68c having a structural pole with horizontal reflectors and verticalreflectors.

The illustrative passive reflector components 14 c seen in FIGS. 12-14can be configured as a combination of passive reflector components 14 aand 14 b. The structural framework for the passive reflector 14 c can afoldable pole arrangement, such as seen in FIG. 4, such as using hollowpoles 82 made of a suitable dielectric material such as fiberglass. Inan illustrative embodiment, an elastic cord 86 is run through thefiberglass tubes 82, serving as a tensioning mechanism. The tubes 82 canbe collapsed and folded for transport and storage, and installed at thelocation by interconnecting the pole segments 82.

The reflector elements 68 c are vertically positioned along the axis ofthe structural pole 62. In the reflector elements 68 c seen in FIGS.12-14, both horizontally-aligned reflector elements 264 andvertically-aligned reflector elements 262 are used.

The horizontally aligned reflector elements 264 can be arranged as apair of crossed metal rods, intersecting at an angle of 90°. In someembodiments, the reflector elements 262 and/or 264 can preferably beconstructed of a metal such as aluminum. The reflector elements 68 c arestacked on the pole as shown in FIG. 12, with an appropriate spacingbetween them. Each of the cross-shaped reflector elements 264 is alignedin the horizontal plane, and is placed perpendicular to the axis Z ofthe structural pole 62. The size, shape, spacing, and grouping of thereflector elements 262,264 are configured to provide the desiredreflectivity characteristics for the frequencies involved, e.g., UHF orgreater that UHF frequencies.

The horizontally aligned reflector elements 262 are combined withvertical reflector elements 264 that are positioned along the axis Z ofthe structural pole 62. In some embodiments, the vertical reflectorelements 262 can include hollow cylindrical tubes constructed of ametal, e.g., aluminum, and placed coaxially and around the structuralpole 62. Alternatively, the reflector elements 68 c can be constructedusing metal or metalized tape affixed around a hollow tube of any of avariety of materials.

The lengths of the reflector elements 68 v can be selected to provideresonance at the desired frequency of operation. In some embodiments,the length can approximate half the wavelength (0.5λ) of the signal, asadjusted by an appropriate adjustment factor corresponding to thematerial of the reflector and its size and thickness. In someembodiments, the vertical distance from one pair of reflector elementsto the next pair can correspond to approximately 0.75 λ adjusted asabove.

An alternative implementation 14 c includes horizontal 264 and vertical262 reflector elements, as illustrated in FIG. 14, wherein the verticalelements 262 are positioned between the horizontal elements 264 insteadof being intersected by them.

In a specific illustrative embodiment, the passive reflector component14 c includes 24 conductive reflector elements with 16 reflectorelements arranged horizontally in eight crossed pairs 264 aligned in thehorizontal plane, 8 reflector elements 262 arranged vertically along theZ axis of the structural framework, 8 dielectric support rods 82 (FIG.4) made of fiberglass, a dielectric support pole to the base, and analuminum support base 70 (FIG. 3).

This implementation uses tubular (hollow) ½″ outer diameter fiberglassrods 82 that provide support for the ⅝″ outer diameter aluminum verticalelements and at the same time dielectrically load the vertical array.This loading provides for shorter vertical element to vertical elementspacing (7″ end to end at 400 MHz) making the entire array shorter andmore compact. The hollow fiberglass rods 82 allow for an elastic shockcord 86 (FIG. 4) to extend through the entire array, providing neededtension for the structure 14 c, as well as ease of packing when stowed.In an illustrative embodiment, an exemplary elastic shock cord 86 forstowable embodiments 14 can be Series No. SC Nylon Shock Cord, such ascurrently available through T. W. Evans Cordage Co., of Cranston RI.

To support an illustrative UHF radio frequency of 400 MHz, the reflectorelement length in the implementation of FIG. 11 can be optimized forresonance to be 13.8″ (horizontal), using a 0.5λ length, adjusted by anadjustment factor of 0.935, and 13.1 (vertical) using an adjustmentfactor of 0.888. The vertical distance between two adjacent reflectorcrossed pairs can be optimized to 20.1″, or 0.75λ using the samevertical adjustment factor. This arrangement provides a total maximumgain of 11.9 dBi. The antenna dimensions including the support structureare 13.8″×13.8″×198.3. In some embodiments of the reflector component 14c seen in FIGS. 12-14, the reflector component 14 c can be placedvertically on the ground within a constrained environment ENV, such aswithin a tunnel, resulting in a small footprint.

FIG. 15 is a chart 300 that shows radiation patterns for vertical m1 andhorizontal m2 radiation patterns for an illustrative embodiment of apassive reflector element having horizontal reflectors and verticalreflectors. The reflector elements of a passive reflector element 14 creflect the signal through a 360-degree arc in the horizontal plane witha slightly higher gain in the −45°/135° axis, providing relativelyuniform coverage in all directions.

Passive Sheet Reflector Components.

FIG. 16 shows 320 an illustrative passive sheet reflector component 14 dthat includes reflector elements 68 d arranged in a two-dimensionalmatrix 322, such as embedded within a flexible sheet backing 362. FIG.17 shows detailed view 340 of a single-reflector element 68 d for anillustrative passive sheet reflector component 14 d. FIG. 18 shows 360 aprototype implementation of an illustrative passive sheet reflectorcomponent 14 d, including a structural sheet 362 and a 4×4 matrix ofcopper tape reflector elements 68 d.

In the passive sheet reflector component 14 d seen in FIGS. 16-18, thestructural framework for the passive UHF reflector component 14 d can bea flat sheet 362, such as a blanket or a tarpaulin made of a suitabledielectric material. The sheet 362 can be folded or rolled into acompact size and shape for ease of transport, and unfolded at thedesired installation site.

The reflector elements 68 d can be placed in a two-dimensional planararrangement 322 across the surface of the structural sheet, as shown inFIG. 16. Each reflector element 68 d seen in FIG. 16 is a rectangularstrip of metal tape affixed to the sheet 362 at a specific location suchas shown in FIG. 17. The size, shape, spacing, and grouping of thereflector elements 68 d are designed to provide the desired reflectivitycharacteristics for the frequencies involved, e.g., UHF or greater thanUHF. The length of the reflector elements 68 d can be selected toprovide resonance at the desired frequency of operation. In someembodiments, the length can approximate half the wavelength (0.5λ) ofthe signal, as adjusted by an appropriate adjustment factorcorresponding to the material of the reflector 68 d and its size andthickness.

An illustrative embodiment 14 d, such as seen in FIG. 16, includessixteen conductive elements 68 d made of copper tape arranged in a 4×4rectangular matrix 322, and a plastic tarpaulin as a structural sheet362 (FIG., 18). To support a desired UHF radio frequency of 400 MHz, thereflector element length can be optimized to be 13.5″ for resonance,using a 0.5λ length, adjusted by an adjustment factor of 0.915. In theillustrative embodiment shown in FIGS. 16 and 17, the width of thereflector element 68 d is 3″. The horizontal and vertical distancesbetween two adjacent reflectors can be optimized to 28.5″and 12″respectively. This arrangement provides a total maximum gain of 14 dBi.The total antenna dimensions not including the support structure areapproximately 4′ by 9′. An illustrative passive sheet reflectorcomponent 14 d can be placed on a wall or suspended as shown in FIG. 18.

FIG. 19 shows 380 a 3D radiation pattern image 382 for an illustrativeembodiment for one reflector element of a passive sheet reflectorcomponent 14 d. FIG. 20 is a chart 400 that shows vertical andhorizontal radiation patterns m1,m2 for a UHF signal 20 in anillustrative embodiment of a passive sheet reflector component 14 d.

FIG. 21 provides a schematic view 420 of an alternate passive sheetreflector component 14 d, and shows a 3D radiation pattern image for acorresponding reflector element 68 d. FIG. 22 is a chart that showsvertical and horizontal radiation patterns for a reflector element ofthe alternate passive sheet reflector component 14 d shown in FIG. 21.The alternate passive sheet reflector component 14 d includes sixteenconductive elements 68 d made of copper tape arranged in a 4×4rectangular matrix, and a plastic tarpaulin 362 as a structural sheet.To support an illustrative UHF radio frequency of 400 MHz, the reflectorelement length can be optimized to be 13.5″ for resonance, using a 0.5λlength, adjusted by an adjustment factor of 0.915. The width of thereflector element is 1″. The horizontal and vertical distances betweentwo adjacent reflectors 68 d can be optimized to 21.5″and 13″respectively. This arrangement provides a total maximum gain of 17.5dBi. The total antenna dimensions not including the support structureare 93″×68.5″×0.01″. The alternate passive sheet reflector component 14d provides greater directionality and gain, as shown by the radiationpatterns in FIG. 21 and FIG. 22.

A further implementation of a passive sheet reflector component 14 d, asshown in FIGS. 23 and 24, includes twelve conductive elements 68 b madeof copper tape arranged in a 3×4 rectangular matrix, and a plastictarpaulin 362 as a structural sheet. To support an illustrative UHFradio frequency of 400 MHz, the reflector element length can beoptimized to be 13.5″ for resonance, using a 0.5λ length, adjusted by anadjustment factor of 0.915. The width of the reflector element is 1″.The horizontal and vertical distances between two adjacent reflectors 68d can be optimized to 21.5″and 13″ respectively. This arrangementprovides a total maximum gain of 15.9 dBi. The total antenna dimensionsnot including the support structure are 66.5″×68.5″×0.01″. Theillustrative passive sheet reflector component 14 d shown in FIGS. 23and 24 provides greater directionality and gain, as shown by theradiation patterns.

Passive Reflector Components having Patch Antenna Panels with GroundPlane.

FIG. 25A and 25B provide schematic front 500 and rear views 520 ofreflector elements for an illustrative embodiment of patch antennapanels 14 e. FIG. 26 shows an illustrative far field 3D radiationpattern 540 for a corresponding patch antenna panel embodiment 14 e.FIG. 27 is a chart 560 that shows vertical and horizontal radiationpatterns for an illustrative embodiment of patch antenna panels 14 e.FIG. 28 shows conceptual 3D radiation patterns 580 for twointerconnected dual patch antenna panels 14 e.

In an illustrative embodiment of the patch antenna panels 14 e, thestructural framework can include a flat sheet 502 of compressible airfoam material, which in some embodiments can have characteristicthickness of 0.25″. In some embodiments, the reflector elements 68 e areconfigured as a conductive ground plane on one side of the structuralframework 502, which in some embodiments is preferably copper foil, andtwo patch elements 68 e on the other side of the structural framework502, which in some embodiments can also preferably include copper foil.

The two dimensional nature of this planar array 14 e results in aversatile structure which is able to provide a high-gain radiationpattern with a strong front lobe and weak side lobes. In someembodiments, the patch antenna panels 14 e can be rolled up and storedin a lightweight tube, allowing easy transport and deployment.

In an illustrative implementation of the patch antenna panels 14 e, eachdual patch panel is 49″×36″, made of 8 mil copper foil on a 0.25″ foamsubstrate as the structural element, with a ground plane also of 8 milcopper foil. FIG. 26 and FIG. 27 show the radiation pattern for onepatch panel with its corresponding ground plane. This arrangementprovides the widest gain with deep pattern nulls at +90° and −90°. FIG.28 shows illustrative radiation patterns for two dual patch antennapanels 14 e, when their corresponding ground planes are interconnected.

Some alternate embodiments of the passive reflector components 14 caninclude structural framework comprising a flat sheet, such as made byweaving a suitable fiber such as Kevlar into a mesh sheet. In some mashembodiments, the reflective elements can include metal or metalizedfibers that are woven into the mesh. The size, shape, spacing, andgrouping of the woven metal wires can be configured to provide thedesired reflectivity characteristics for the UHF frequencies involved,e.g., UHF or greater than UHF. In one variation, the arrangement of thereflector elements can be in a 4×4 matrix of the rectangular reflectorelements 68, in a manner similar to that of sheet embodiments 14 d,which can be hung or be placed on a wall.

Other embodiments of the passive reflector components 14 can include astructural framework provided by a rope made of a suitable material,such as Kevlar™ or fiberglass. In an illustrative embodiment, thereflector elements are metal or metalized wires that can be introducedamong the fibers to provide a preferred arrangement of reflectorelements. The size, shape, spacing, and grouping of the metal wireswithin the rope are designed to provide the desired reflectivitycharacteristics for the UHF frequencies involved, e.g., UHF or greaterthan UHF. In such an embodiment, the wire mesh rope reflector component14 can be hung from the ceiling of the tunnel ENV, potentially allowingit to be out of the way and be less prone to damage from collisions withvehicles or people traveling through the tunnel.

Passive Reflector Components with Inflatable Puck.

FIG. 29 provides a schematic view 600 of a passive reflector component14 f that includes an inflatable puck 602 having deployable structuralelements 606 and reflector elements 68 f. When deployed 9 FIG. 3), theflexible membrane 610 can be inflated to its full height. FIG. 30 shows610 a plurality of inflatable pluck passive reflector components 68 f intheir deployed state.

In the illustrative passive reflector component 14 f seen in FIGS. 29and 30, the structural framework 606 includes a thin-walled plastic tube606 that can be made rigidly inflated, such as using pressurized air oranother pressurized gas (e.g., a carbon dioxide cartridge) 604, ordeflated and collapsed to a small size for transport and storage (FIG.29).

The reflector elements 68 f are vertically positioned along the axis ofthe inflatable structural pole 606. In some embodiments, the reflectorelements 68 f can be made of flexible metal tape such as copper tape,affixed to the outer surface of the structural plastic tube 606, to formcylindrical metal tubes when the structural pole 606 is inflated.

As seen in FIG. 29, the base 602 of the illustrative passive reflectorcomponent 14 f contains a compressed gas reservoir 604, which can beused to deploy a flexible membrane 606 with reflector elements 68 fpositioned through its length. Upon deployment, the gas inflates themembrane 606, forming a long rigid tube rising above its container 602,as shown in FIG. 30. The reflector elements 68 f can be placed coaxiallyand around the structural pole and are stacked on the pole, such as in amanner resembling the passive reflector component 14 a. As seen in FIG.30, one or more passive reflector component 14 f can be placed on theground, such as within a constrained environment ENV.

Flat Panel Passive Reflector Components.

FIG. 31 provides a schematic view of a flat panel passive reflectorcomponent 14 g, using a metallized reflector element 682 and a plastictarpaulin structural element 684, which can be hung or mounted to a wallwithin a constrained environment ENV. The structural framework 684 forthe passive reflector component 14 g can be provided as a flat sheet684, such as a blanket or a tarpaulin made of a suitable dielectricmaterial. The sheet 684 can be folded into a compact size and shape forease of transport, and unfolded at the desired installation site ENV.

The illustrative reflective element 682 typically comprises a flat panelof metalized, biaxially-oriented polyethylene terephthalate, commonlyknown by the brand name Mylar™, which is attached to the structuralsheet 684. This approach and construction differs from flat panelpassive reflector components 14, e.g., 14 d, which in some embodimentuse rigid sheets of aluminum 68 d.

The flat panel reflector component 14 g can be used for a range offrequencies and also provides the highest gain. The upper frequencylimitation is a function of reflector flatness. In an illustrativeembodiment, surface gaps or roughness must be less than λ/10. At 400MHz, λ=29.5″ so flatness must be better than 3″. In such an embodiment,at 2300 MHz, λ=5.13″ so flatness must be better than 0.5″.

In some embodiments, the illustrative flat panel reflector component 14g shown in FIG. 31 uses standard off the shelf survival metalized mylarthermal blankets (˜0.5 mil thick). The implementation is designed to beused at communication frequencies of 400 MHz and S-Band (1.8 to 2.3GHz). The area of the flat panel reflector can be designed according tothe equation

-   -   Gr=22.2+40 log(f)+20 log(A)+20 log(cos θ)    -   where    -   Gr=desired two-way gain of reflector in dBi    -   F=frequency in GHz    -   A=area of passive reflector in square feet; and    -   θ=½ of the included angle between the incident and reflected        paths

Dual Pole Vertical Reflector Components.

FIG. 32 provides a schematic view 700 of duel pole passive reflectorcomponents 14 h, wherein each passive reflector component 14 h includesa structural pole with coaxially-positioned dual reflectors 68. In thisembodiment 14 h, the structural framework 62 for the passive reflectors68 can readily be configured as foldable pole arrangement (FIG. 4), oras an inflatable puck 602 (FIG. 29). The illustrative structuralarrangement 62 in FIG. 32 includes two poles 62 spaced at a measured orpredetermined distance from each other. As similarly shown in FIG. 4,each of foldable poles can be configured using hollow poles 82 made of asuitable dielectric material such as fiberglass. In some embodiments, anelastic cord 86 is run through the hollow fiberglass poles 86, to serveas a tensioning mechanism. The tubes 821 can be collapsed and folded fortransport and storage, and installed at the location by interconnectingthe pole segments

In puck component embodiments 14 h, each of the pair of inflatable pucks602 can include a thin-walled plastic tube 606 that can be made rigidlyinflated, such as using pressurized air or another pressurized gas(e.g., a carbon dioxide cartridge) 604, or deflated and collapsed to asmall size for transport and storage.

The reflector elements 68 are vertically positioned along the axis ofthe structural pole 62. In some embodiments, the reflector elements 68are preferably hollow cylindrical tubes constructed of a metal such asaluminum and placed coaxially and around the structural pole 62.Alternatively, the reflector elements 68 can be constructed using metalor metalized tape affixed around a hollow tube of any of a variety ofmaterials. In some embodiments, the reflector elements 68 can bearranged as dual elements, e.g., two elements abutting each other,stacked on each of the two poles 68, as shown in FIG. 32, with anappropriate spacing between each pair of dual elements 68.

The length of the reflector elements 68 can be selected to provideresonance at the desired frequency of operation. In some embodiments,the length can preferably approximate half the wavelength (0.5λ) of thesignal, as adjusted by an appropriate adjustment factor corresponding tothe material of the reflector 68 and its size and thickness. Thedistance from the center of one reflector element 68 to the center ofthe next reflector element 68 can correspond to approximately 0.75λ,which can be adjusted as discussed above.

A specific illustrative embodiment of the dual-pole reflector componentincludes eight aluminum reflector elements 68, eight dielectricfiberglass support poles 62, and two aluminum support bases 70 (FIG. 3).

To support an illustrative UHF radio frequency of 400 MHz, the reflectorelement length can be optimized to be 13.1″ for resonance, using a 0.5λlength, adjusted by an adjustment factor of 0.888. The center-to-centerdistance between two adjacent reflectors can be optimized to 20.1″, or0.75λ using the same adjustment factor. The two support poles are placed42″ apart. This arrangement provides a total maximum gain of 11.0 dBi.The antenna dimensions including the support structure are42″×0.625″×80″.

FIG. 33 shows 3D radiation patterns 720 for one reflector element in aduel pole passive reflector. FIG. 34 is a chart 740 that shows verticaland horizontal radiation patterns for one reflector element of anillustrative dual pole reflector assembly.

FIG. 35 is a schematic diagram 780 for illustrative placement of a dualpole reflector assembly 14 h within a constrained environment ENV. Fig,35 also shows corresponding radiation patterns and preferredcommunication directions for a dual pole reflector assembly 14 h. Asseen in FIG. 35, one or more dual pole reflector assembly 14 h can beplaced on the ground in a tunnel network ENV.

Helical Wire Reflector Components.

FIG. 36A and 36B are schematic diagrams 800,820 for illustrative helicalwire reflector components 14 i. In this embodiment 14 i, the structuralframework 62 for the passive helical wire reflectors 802 can readily beconfigured as foldable pole arrangement (FIG. 4), or as an inflatablepuck 602 (FIG. 29).

In this embodiment 14 i, the structural framework 62 for the passivehelical wire reflectors 802 can readily be configured as foldable polearrangement (FIG. 4), or as an inflatable puck 602 (FIG. 29).

The foldable pole arrangement uses hollow poles 82 made of a suitabledielectric material such as fiberglass. An elastic cord is run throughthe hollow fiberglass poles, serving as a tensioning mechanism. Thetubes 82 can be collapsed and folded for transport and storage, andinstalled at the location by interconnecting the pole segments 82.

The inflatable puck structural arrangement uses a thin-walled plastictube 606 (FIG. 29 that can be made rigidly inflated, such as usingpressurized air or another pressurized gas (e.g., a carbon dioxidecartridge) 604, or deflated and collapsed to a small size for transportand storage.

The reflector elements 802 are made of conductive wire that can behelically wound around the structural pole 62 and/or verticallypositioned along the axis of the inflatable structural pole 606 as shownin FIG. 36B.

As an example, a specific implementation 14 i includes four separatehelical turn wires 802, which can be mounted around an inflatable tube606, that serves as the structural element 62.

FIG. 37 shows 3D radiation patterns 840 for one helical wire reflectorelement associated with a helical wire reflector component. FIG. 38 is achart 860 that shows vertical and horizontal radiation patterns for onehelical wire reflector element associated with a helical wire reflectorcomponent 14 a. To support an illustrative UHF radio frequency of 400MHz, the reflector element length can be optimized to be 13.5″ forresonance, using a 0.5λ length, adjusted by an adjustment factor of0.915. The end-to-end distance between two adjacent reflectors can beoptimized to 12.6″. This arrangement provides a total maximum gain of8.6 dBi. In some embodiments, the helical wire reflector components 14 ican be placed on the ground, such as within a constrained environmentENV.

Rapid Deployment Methods.

The passive reflectors of the various embodiments above can be deployedby a person or in an automated manner.

In some embodiments, a person USR can travel through the tunnels,installing the passive reflectors 14 at appropriate locations within aconstrained environment ENV, such as at corners, at intersections, atpredetermined positions, or at locations where a signal detectorindicates diminished reception.

For instance, a signal source can be established at the entrance to amine, and is set up to emit radio waves at a determined frequency. Avehicle that can traverse the mine tunnels is outfitted with tworeceivers, one at the front and one at the rear of the vehicle. A numberpassive reflectors 14 are carried on the vehicle or by a human fordeployment. As the vehicle travels through the tunnels, there will belocations where the front receiver passes outside the range of thesource signal while the rear receiver still has reception. The passivereflectors 14 can be deployed at this location, as it would be wellsuited for the installation of a repeater system.

In some embodiments, the deployment of illustrative embodiments of thepassive reflector components 14 can be carried out by an occupant of thevehicle, or dropped from a vehicle driving through the space. Automaticdeployment can take place when a turn is made, or a sensor detects thatthe received signal has diminished to need a reflector 14. The sensorcan be mounted on the front of the vehicle to give time for reflectorsto be deployed from the rear before going around the corner of a tunnel.Embodiment 8 (the inflatable puck) can be enabled to inflate and deployautomatically when dropped on the ground.

Passive reflector components 14 can be designed in form factors that arecompact to transport and at the same time are amenable to automatic,quick deployment or unfurling. For example, the above-described approachcan also be used with the foldable pole and sheet passive reflectordesigns. In particular, the sheet designs of reflector componentembodiments 14 d, 14 e and 14 g can be quickly deployed by attaching thetop edge to a wall and allowing gravity to unroll and thus deploy them.

In other system embodiments 10, embodiments 15 that are based on a sheetor mesh system can be implemented on a mesh fabric panel with a flexibleframe that can be twisted into a compact shape and that, when released,unfolds into its full size. In another variation, a self-rightingpyramid structure can be used as the structural framework. When droppedto the ground, the system arranges itself into a configuration that isconducive to passive reflection of the desired frequencies.

Alternative Embodiments

While the invention is described above in the context of radiocommunications in underground and constrained environments such as minetunnels, the invention can also be extended to a variety of otherapplications. Some examples are provided in this section.

Deployment in a Diversity of Devices and Frequencies.

While the deployment of embodiments of the invention are described asmultiple instances of the same embodiment, it will readily be seen thatdifferent embodiments of the passive reflector components can beutilized and can work together to provide a specific communicationrequirement.

As an example, a tunnel may have sections that are tall and narrow,where implementations of passive reflector components 14 a,14 b,14 cand/or 14 h can be deployed, as well as other sections that are low withwalls that accommodate passive reflector components 14 d,14 e,14 fand/or 14 i.

Embodiments of the passive reflector components 14 can also work inconjunction with other equipment that operates in the same frequency. Asan example, embodiments of the passive reflector components 14 may beused along with active repeaters, providing a flexible solution to userswho may have a diverse inventory of available equipment.

The passive reflector components 14 provide gain and signal reflectivitycapability in a range of frequencies around the specific frequency theyare designed for. This permits flexibility in the choice of signalfrequencies.

Exploration of Caves and Underground Complexes.

The exploration and survey of underground features such as caves,tunnels, cenotes, lava tubes, and abandoned mines, is carried out inconstrained conditions, with little or no knowledge of the terrain andthe layout of underground pathways. In such applications, radio signalsfrom an external source will have limited reach, and repeaters will beneeded to ensure communications for the exploring party. It will beimpractical for an exploring party to carry arbitrary numbers of activerepeater equipment with associated wiring or battery systems and deploythem to maintain radio communications with the surface. The variousembodiments of the portable deployable underground communication systemdescribed above can be more easily carried in large numbers, deployedquickly as required at locations, take up little space in constrainedenvironments, and provide passive performance.

Search and Rescue.

Some embodiments of the invention can be utilized in search and rescuemissions. For example, an earthquake in an urban area may result indamage to existing communications and electrical infrastructure. Asrescue crews navigate the rubble, they would benefit from portabledeployable radio communication systems that could provide an effectivecommunications link to a base location. Rescuers would be able to carrylightweight systems that would auto-deploy when positioned, and bydeploying them at regular intervals, adequate signal strength can beobtained. Similar applications can also be considered in search andrescue operations in outdoor environments such as wooded areas,mountainous terrain, or even open country where communications and powerinfrastructure are not readily available and the needs of the situationare rapidly evolving.

Communications in Mountainous Terrain.

Practical applications of the disclosed passive reflector communicationssystems can also be found in mountainous or otherwise challengingterrain where line of sight communications may be occluded by natural orman-made features. For example, it is common for mobile cellulartelephone signals to have limited reach in mountainous regions, even inlarge urban areas where communications infrastructure is typicallydensely available. For example, a narrow valley branching out of acanyon can serve a small population of residents. A passive reflectorsystem would be a practical and effective solution. Further, theinvention's portability and deployability characteristics allowinstallation in potentially constrained locations such as high ridges ornarrow roadside walls in canyons. As an example, passive reflectorcomponent 14 d can be deployed on a water tower to provide coverage inchallenging terrain.

Covert and Military Operations.

In covert or military operations, there may be an existing radiocommunications infrastructure; however, it may be unavailable to themilitary team who will need to operate using different equipment andradio frequencies. The team can carry portable radios operating in asecure band, and use the portable deployable passive reflectors of theinvention to extend signal coverage to their evolving areas ofoperation. This solution has the additional benefit that the discoveryor capture of the passive reflector systems by an adversary will nothave the effect of compromising the secure communications frequency forfuture missions, as no active equipment is left behind.

System Testing and Alternate Embodiments.

FIG. 39 is a schematic diagram 880 of a deployed balloon reflectorcomponent 14 j in a tunnel network, which includes vertical stripreflectors 68 j, e.g., for L-Band or S-band operation, that are attachedto a balloon 882, in which the balloon 882 can be deployed 890 within aconstrained environment ENV, such as from a deployment module 886, suchas a puck structure 886 containing one or more gas cylinders 906, e.g.,helium cartridges 904 and a corresponding balloon inflation mechanism902. FIG. 40 is a schematic view 900 of a deployment module 886 for aballoon reflector component 14 j. In some illustrative embodiments ofthe balloon reflector components 14 j, the vertical strip reflectors 68j are optimized for S-Band operation, in which the vertical stripreflectors 68 j are 2.25″L×¼″W, with 2.5″ space between elements. Insome illustrative embodiments of the balloon reflector components 14 j,the vertical strip reflectors 68 j are optimized for L-Band operation,in which the vertical strip reflectors 68 j are 3.95″L×¼″W, with 4.5″space between elements.

Different embodiments of passive reflector components 14 were installedand tested within an underground environment ENV, to investigatedifferent methods for underground communication in the L-band and S-Bandfrequency range. The testing was performed using an array ofself-supporting planar tarp components 14 and helium balloon multi-bandvertical strip reflectors 14 j.

The wireless radios 18 used during the testing were Model MPUS WaveRelay Networked and Digitally Encrypted communication radios 18, e.g.,18 a, 18 b (FIG. 1), available through Persistent Systems LLC, of NewYork, N.Y. During the testing, one of the radios 18 a was located in afixed position, while the other radio 18 b was movable within theconstrained environment ENV. Two computers were also used, one toprogram the radio's RF modules, and the other to monitor and record thesignal to noise ratio (SNR) of the MPU5s 18.

During some of the testing procedures, the radios 18 were evaluated atboth 1370 and 2400 MHz, in which the first radio 18 a was locatedapproximately 1000 feet from a 90 degree turn, at a fixed position, andwin which starting position of the second radio 18 b was line-of-sightor 1000 feet away from the first radio 18 a at a 90 degree turnposition, then moved away to a maximum distance of 2000 feet from the 90degree turn (or 3000 feet total distance away from the first radio'sposition). Signal to Noise Ratio (SNR) data for the signals 20 wasrecorded as the second radio 18 b moved further away from the 90 degreeturn location. This testing was repeated, both without and withdifferent embodiments of passive reflector components 14 located at the90 degree location.

The results of the testing indicated an increased distance of at leastthree times for voice communication using the passive reflectorcomponents 14. For example, without the use of passive reflectorcomponents 14 during testing, loss of communications occurred at 1300 to1400 feet.

For similar test conditions, with the use of passive reflectors 14, noloss of communications occurred at 3000 feet, which was the maximumavailable tunnel distance. There was still a 12 to 25 dB communicationsmargin at 3000 feet (dependent on reflector size and frequency).

Design and evaluation can also be carried out on different sizes andtypes of passive reflector components 14, to provide expectedunderground communications coverage vs. aperture, in an existing tunnelor other constrained environment ENV. For instance, the performance ofdifferent passive reflector components 14 can be evaluated for differentshaped tunnels, such as to provide optimal passive reflectors andpolarization guide lines.

The following is a summary of performance and technical details of thetested L & S Band High Gain Tarp Reflectors:

L & S Band Maximum Digital Voice Communication Coverage withoutReflector:

-   -   1300 to 1400 feet (1000 feet to 90 deg turn then an additional        300 to 400 feet).

L & S Band Minimum Digital Voice Communication Coverage with Reflector:

-   -   3000 feet (1000 feet to 90 deg turn [at Reflector] then an        additional 2000 feet)    -   CW Signal to Noise Ratio at 3000 feet: 35 to 37 dB (L-Band) and        40 to 42 dB (S-Band)    -   MPU5—Digital Voice Communication Margin at 3000 feet: 25 to 27        dB (L-Band) and 30 to 32 dB (S-Band).

L & S Band Tarp Reflector Details (usable for either Horizontal orVertical polarization):

-   -   Size: 8×8 feet w/support, 6×8 feet (reflector), deployed in        horizontal polarization    -   Number of Elements: 121 (L-Band), 380 (S-Band)    -   Directivity: Analysis predicts 26 dBi (L-Band), 31 dBi (S-Band)    -   Reflector Materials: Polyethylene w/reinforced fiberglass and        0.001″ thick Cu elements.

The following is a summary of performance and technical details of thetested L & S Band—Dual Band Vertical Strip Reflectors:

L & S Band Maximum Digital Voice Communication Coverage withoutReflector:

-   -   1300 to 1400 feet (1000 feet to 90 deg turn then an additional        300 to 400 feet).

L & S Band Minimum Digital Voice Communication Coverage with Reflector:

-   -   3000 feet (1000 feet to 90 deg turn [at Reflector] then an        additional 2000 feet)    -   CW Signal to Noise Ratio at 3000 feet: 22 to 24 dB (L-Band) and        24 to 26 dB (S-Band)    -   MPU5—Digital Voice Communication Margin at 3000 feet: 12 to 14 d        B (L-Band) and 14 to 16 dB (S-Band)

L & S Band Vertical Strip Reflector Details:

-   -   Size: 0.25 inch wide×12 feet tall (reflector)    -   Number of Elements: 18 (L-Band), 31 (S-Band)    -   Directivity: Analysis predicts 15 dBi (L-Band), 17 dBi (S-Band)    -   Reflector Materials: Nylon ribbon with 0.001″ thick Cu elements    -   Weight: 15 grams each (L/S-Band vertical arrays)

Unless contrary to physical possibility, it is envisioned that (i) themethods/steps described above may be performed in any sequence and/or inany combination, and that (ii) the components of respective embodimentsmay be combined in any manner.

Note that any and all of the embodiments described above can be combinedwith each other, except to the extent that it may be stated otherwiseabove or to the extent that any such embodiments might be mutuallyexclusive in function and/or structure.

Although the present invention has been described with reference tospecific exemplary embodiments, it will be recognized that the inventionis not limited to the embodiments described, but can be practiced withmodification and alteration within the spirit and scope of the appendedexamples. Accordingly, the specification, drawings, and attachedappendices are to be regarded in an illustrative sense rather than arestrictive sense.

1. A method of operating a communication system, comprising: emitting asource signal from a first location within an environment via a signalemittance device; transporting at least one reflector device within theenvironment, via a vehicle, wherein the at least one reflector device iscoupled to the vehicle; receiving a plurality of distinct signalreception measurements from a plurality of distinct signal receiversrespectively, wherein the plurality of distinct signal receivers arecoupled to the vehicle; sensing at least one location for deployment ofthe at least one reflector device, by determining a difference betweensignal reception received from the plurality of distinct signalreceivers; automatically deploying the at least one reflector device atthe at least one sensed location by uncoupling at least one reflectordevice from the vehicle at the at least one sensed location; andpropagating a communication signal through the communication system viathe at least one deployed reflector device.
 2. The method of claim 1,wherein said transporting further comprises transporting the at leastone reflector device in a compact form.
 3. The method of claim 2,wherein said automatically deploying at least one reflector devicefurther comprises expanding the at least one reflector device from thecompact form.
 4. The method of claim 3, wherein said sensing at leastone location further includes sensing when a received propagatedcommunication signal has diminished.
 5. The method of claim 1, whereinsaid sensing at least one location includes sensing a diminished signalreception from the determined difference between signal receptionreceived from the plurality of distinct signal receivers.
 6. The methodof claim 1, wherein the propagating includes: passively reflecting thecommunication[[s]] signals between the at least one reflector device andanother reflector device and/or a wireless communication device.
 7. Themethod of claim 6, wherein the communication signals include radio wavefrequencies.
 8. The method of claim 1, wherein the at least onereflector device includes a plurality of reflector devices, the methodfurther comprising: sensing a plurality of locations for deployment ofthe plurality of reflector devices; deploying one or more of theplurality of reflector devices at one or more of the plurality of sensedlocations for deployment; and further propagating the communicationsignal through the communication system by using the plurality ofreflector devices.
 9. The method of claim 8, wherein the deploying oneor more of the plurality of reflector devices further comprises:automatically inflating a structure of at least one reflector device.10. The method of claim 1, wherein said deploying at least one reflectordevice further comprises: deploying a reflector array, wherein thereflector array includes a plurality of interconnected reflectorelements; and deploying a structural framework to support and orient thereflector array, wherein the structural framework includes a supportstructure between the plurality of interconnected reflector elements.